java对称加密DES/3DES/AES

1、对称密码算法简介

对称密码算法是当今应用范围最广，使用频率最高的加密算法。它不仅应用于软件行业，在硬件行业同样流行。各种基础设施凡是涉及到安全需求，都会优先考虑对称加密算法。

对称密码算法的加密密钥和解密密钥相同，对于大多数对称密码算法，加解密过程互逆。

（1）加解密通信模型

 

（2）特点：算法公开、计算量小、加密速度快、加密效率高

（3）弱点：双方都使用同样密钥，安全性得不到保证

对称密码有流密码和分组密码两种，但是现在普遍使用的是分组密码： 

2、常用对称密码：

 （1）DES（Data Encryption Standard，数据加密标准）

 （2）3DES（Triple DES、DESede，进行了三重DES加密的算法）

 （3）AES（Advanced Encryption Standard，高级数据加密标准，AES算法可以有效抵制针对DES的攻击算法）

三种算法的简单对比：

 

         

算法	密钥长度	默认密钥长度	工作模式	填充方式
DES	56	56	ECB、CBC、PCBC、CTR、CTS、CFB、CFB8-CFB128、OFB、OFB8-OFB128	NoPadding、PKCS5Padding、ISO10126Padding
3DES	112、168	168	ECB、CBC、PCBC、CTR、CTS、CFB、CFB8-CFB128、OFB、OFB8-OFB128	NoPadding、PKCS5Padding、ISO10126Padding
AES	128、192、256	128	ECB、CBC、PCBC、CTR、CTS、CFB、CFB8-CFB128、OFB、OFB8-OFB128	NoPadding、PKCS5Padding、ISO10126Padding

 

3、实例：

package com.its.common.crypto.symmetry;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

/**
 * 对称加密(AES/DES/3DES) 推荐使用AES
 */
public class SymmetryUtil {
	public static String ALGORITHM_AES = "AES";
	public static String ALGORITHM_DES = "DES";
	public static String ALGORITHM_3DES = "DESede";
	public static String KEY = "QWE!@#123qwe123@*()342%";

	/**
	 * 创建密钥key对象
	 * 
	 * @param algorithm
	 * @param keysize
	 * @param key
	 * @return
	 * @throws NoSuchAlgorithmException
	 */
	public static SecretKey createKey(String algorithm, int keysize, String key) {
		KeyGenerator keyGenerator = null;
		SecretKey secretKey = null;
		try {
			keyGenerator = KeyGenerator.getInstance(algorithm);
			keyGenerator.init(keysize, new SecureRandom(key.getBytes()));
			secretKey = keyGenerator.generateKey();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return secretKey;
	}

	public static byte[] encrypt(String algorithm, int keysize, String key, byte[] data) {
		try {
			SecretKey secretKey = createKey(algorithm, keysize, key);
			Cipher cipher = Cipher.getInstance(algorithm);
			cipher.init(Cipher.ENCRYPT_MODE, secretKey);
			byte[] encryptByte = cipher.doFinal(data);
			return encryptByte;
		} catch (Exception e) {
			System.out.println("exception:" + e.toString());
		}
		return null;
	}

	public static byte[] decrypt(String algorithm, int keysize, String key, byte[] data) {
		try {
			SecretKey secretKey = createKey(algorithm, keysize, key);
			Cipher cipher = Cipher.getInstance(algorithm);
			cipher.init(Cipher.DECRYPT_MODE, secretKey);
			byte[] decryptByte = cipher.doFinal(data);
			return decryptByte;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	public static String encrypt(String algorithm, int keysize, String key, String data) {
		byte[] encryptByte = encrypt(algorithm, keysize, key, data.getBytes());
		String encryptStr = encryptBASE64(encryptByte);
		return encryptStr;
	}

	public static String decrypt(String algorithm, int keysize, String key, String data) {
		byte[] decryptByte = decrypt(algorithm, keysize, key, decryptBASE64(data));
		String decryptStr = new String(decryptByte);
		return decryptStr;
	}

	/** 字节转字符 */
	public static String byteToHexString(byte[] bytes) {
		StringBuffer sb = new StringBuffer(bytes.length);
		String sTemp;
		for (int i = 0; i < bytes.length; i++) {
			sTemp = Integer.toHexString(0xFF & bytes[i]);
			if (sTemp.length() < 2) {
				sb.append(0);
			}
			sb.append(sTemp.toUpperCase());
		}
		return sb.toString();
	}

	/** 字节转字符 */
	public static String encryptBASE64(byte[] data) {
		return new BASE64Encoder().encodeBuffer(data);
	}

	/** 字符转字节 */
	public static byte[] decryptBASE64(String data) {
		try {
			return new BASE64Decoder().decodeBuffer(data);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
}

package com.its.test.crypto.symmetry;

import org.junit.Test;

import com.its.common.crypto.symmetry.SymmetryUtil;

public class SymmetryUtilTest {

	/** 将字符加密后为字节--再将字节解密为字符 */
	@Test
	public void testByte() {
		testAES();
		testDES();
		test3DES();
	}

	public void testAES() {
		String data = "Tzz123456~!@#$%^&*()_+-={}|[]:'<>?,./asdkdk";
		System.out.println("AES");
		System.out.println("加密前：" + data);
		byte[] encrypted = SymmetryUtil.encrypt(SymmetryUtil.ALGORITHM_AES, 128, SymmetryUtil.KEY, data.getBytes());
		System.out.println("加密后：" + SymmetryUtil.byteToHexString(encrypted));
		byte[] decrypted = SymmetryUtil.decrypt(SymmetryUtil.ALGORITHM_AES, 128, SymmetryUtil.KEY, encrypted);
		System.out.println("解密后：" + new String(decrypted) + "\n");
	}

	public void testDES() {
		String data = "PLaa456963~!@#$%^&*()_+-={}|[]:'<>?,./asdkdk";
		System.out.println("DES");
		System.out.println("加密前：" + data);
		byte[] encrypted = SymmetryUtil.encrypt(SymmetryUtil.ALGORITHM_DES, 56, SymmetryUtil.KEY, data.getBytes());
		System.out.println("加密后：" + SymmetryUtil.byteToHexString(encrypted));
		byte[] decrypted = SymmetryUtil.decrypt(SymmetryUtil.ALGORITHM_DES, 56, SymmetryUtil.KEY, encrypted);
		System.out.println("解密后：" + new String(decrypted) + "\n");
	}

	public void test3DES() {
		String data = "Tzz123456~!@#$%^&*()_+-={}|[]:'<>?,./asdkdk";
		System.out.println("3DES");
		System.out.println("加密前：" + data);
		byte[] encrypted = SymmetryUtil.encrypt(SymmetryUtil.ALGORITHM_3DES, 168, SymmetryUtil.KEY, data.getBytes());
		System.out.println("加密后：" + SymmetryUtil.byteToHexString(encrypted));
		byte[] decrypted = SymmetryUtil.decrypt(SymmetryUtil.ALGORITHM_3DES, 168, SymmetryUtil.KEY, encrypted);
		System.out.println("解密后：" + new String(decrypted));
	}

	/** 将字符加密后为字符--再将字符解密为字符 */
	@Test
	public void testStr() {
		testAESToStr();
	}

	public void testAESToStr() {
		String data = "Tzz123456~!@#$%^&*()_+-={}|[]:'<>?,./asdkdk";
		System.out.println("AES");
		System.out.println("加密前：" + data);
		String encrypted = SymmetryUtil.encrypt(SymmetryUtil.ALGORITHM_AES, 128, SymmetryUtil.KEY, data);
		System.out.println("加密后：" + encrypted);
		String decrypted = SymmetryUtil.decrypt(SymmetryUtil.ALGORITHM_AES, 128, SymmetryUtil.KEY, encrypted);
		System.out.println("解密后：" + decrypted + "\n");
	}

}